Carbothermic formation of boron nitride

Abstract Formation of boron nitride by reaction of boric oxide with carbon and nitrogen was studied. It was found from the results of experiments conducted by holding B 2 O 3 -activated C mixtures under a flowing nitrogen atmosphere that formation of boron nitride was complete in 120 min at 1500 °C. After cleaning the reaction product from the ash of the activated carbon and from the unreacted B 2 O 3 pure BN powder was obtained. B 4 C was found to exist as an intermediate species in the reaction products of the experiments in which BN formation was not complete. The results of experiments conducted with the objective of gaining an insight into the reaction mechanism by using different geometrical arrangements show that liquid B 2 O 3 and solid carbon need not be in contact in the formation of BN from B 2 O 3 , C and N 2 and indicate that the reaction proceeds through a gaseous boron containing species which is most probably B 2 O 3 (g).